text: The reaction of the CFCs which is responsible for the depletion of ozone, is the photo-induced scission of a C-Cl bond:
  :CClF → CClF + Cl
  The chlorine atom, written often as Cl, behaves very differently from the chlorine molecule (Cl). The radical Cl is long-lived in the upper atmosphere, where it catalyzes the conversion of ozone into O. Ozone absorbs UV-B radiation, so its depletion allows more of this high energy radiation to reach the Earth's surface. Bromine atoms are even more efficient catalysts; hence brominated CFCs are also regulated.